Related Experiment Video
Updated: Jul 18, 2026

Antibiotic Efficacy Testing in an Ex vivo Model of Pseudomonas aeruginosa and Staphylococcus aureus Biofilms in the Cystic Fibrosis Lung
Published on: January 22, 2021
In vitro activity of tigecycline against quinolone-resistant Streptococcus pneumoniae, methicillin-resistant
Mark W Garrison1, Joshua J Nuemiller
1Washington State University, College of Pharmacy and Deaconess Medical Center, Spokane, WA 99210, USA. garrism@wsu.edu
Abstract:
Tigecycline is a glycylcycline with promising broad-spectrum activity, including resistant Gram-positive organisms. This study characterizes in vitro activity of tigecycline against quinolone-resistant Streptococcus pneumoniae (QRSP), methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecalis (VRE). An in vitro pharmacodynamic model generated specific bacterial kill profiles for tigecycline against clinical isolates of QRSP, MRSA and VRE. Tigecycline produced a 6.6 log total reduction and cleared QRSP from the pharmacodynamic model by 18 h. Tigecycline and vancomycin were unable to achieve 3-log reductions in the MRSA and VRE isolates; log reductions in MRSA and VRE were 1.5 and 1.2 logs for tigecycline and 2.8 and zero for vancomycin, respectively. Area under the concentration time curve to minimum inhibitory concentration (AUC/MIC) values for tigecycline ranged from 79 to 158 microg h/mL and tigecycline concentrations remained above the MIC (T>MIC) throughout the simulated dosing interval. Tigecycline showed in vitro activity against the QRSP, MRSA and VRE isolates studied. Low MIC values, prolonged elimination half-life and the associated post-antibiotic effect (PAE) observed with tigecycline are desirable attributes that make it a potentially attractive option for treating resistant Gram-positive organisms.
Related Concept Videos
Mechanism of Antibiotic Resistance in MRSA
Clinical Significance of Antibiotic Resistance
Inhibitors of Gram-positive Cell Wall Synthesis
Gene Regulation in Microbial Communities: Quorum Sensing
Development of Antibiotic Resistance
Antimicrobial Effectiveness